The McDonald Ranch House, also known as Trinity Site, in the Oscura Mountains of Socorro County, New Mexico, was the location of assembly of the world's first nuclear weapon. The active components of the Trinity test "gadget", a plutonium Fat Man-type bomb similar to that later dropped on Nagasaki, Japan, were assembled there on July 13, 1945. The completed bomb was winched up the test tower the following day and detonated on July 16, 1945 as the Trinity nuclear test.

The McDonald Ranch House, also known as Trinity Site, in the Oscura Mountains of Socorro County, New Mexico, was the location of assembly of the world's first nuclear weapon. The active components of the Trinity test "gadget", a plutonium Fat Man-type bomb similar to that later dropped on Nagasaki, Japan, were assembled there on July 13, 1945. The completed bomb was winched up the test tower the following day and detonated on July 16, 1945 as the Trinity nuclear test. The McDonald Ranch House was built in 1913 by Franz Schmidt, a German immigrant, and acquired by the McDonald family in the 1930s. The ranch was vacated by the McDonald family under protest in 1942, when the United States Army took over the land as part of the Alamogordo Bombing and Gunnery Range to use in training bomber crews during World War II. The family hoped that the ranch would be returned after the war, but it was not, and in 1970, the Army announced that it would be kept permanently. The McDonald Ranch House was empty and deteriorating until 1982, when it was stabilized by the Army. In 1984 it was restored by the National Park Service to appear as it did on July 12, 1945. The site is now open to visitors twice a year, on the first Saturday in April and October. (en)

The McDonald Ranch House, also known as Trinity Site, in the Oscura Mountains of Socorro County, New Mexico, was the location of assembly of the world's first nuclear weapon. The active components of the Trinity test "gadget", a plutonium Fat Man-type bomb similar to that later dropped on Nagasaki, Japan, were assembled there on July 13, 1945. The completed bomb was winched up the test tower the following day and detonated on July 16, 1945 as the Trinity nuclear test. (en)